A case of gout in a 15-year-old boy with juvenile idiopathic arthritis

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SCIENCE
A case of gout in a 15-year-old boy with juvenile idiopathic arthritis

A 15-year-old obese Hispanic young man presented to the orthopedic surgery service with right-sided ankle pain. His pain began after a sports injury approximately one year prior to presentation but did not respond to immobilization, physical therapy or prolonged rest. The pain was located at the medial side of the ankle, was worse with activity, and was accompanied by intermittent swelling. He took ibuprofen at night occasionally that provided modest relief. His uric acids levels were high and also elevated CRP 6.7 mg/dL, WBC 12.6 K/uL, Hgb of 12.3 g/dL, and ESR of 61 mm/hr were reported. ANA, dsDNA, and HLA-B27 were negative.

The most likely diagnosis of this presentation is

  • Fibromylagia
  • Joint Fractures
  • Gout and Juvenile Idiopathic Arthritis
  • Ankylosing Spondylytis

Introduction

In the pediatric population, there are various reasons of joint pain, stiffness, and swelling. Numerous can be attributed to minor activity or overuse-related injury, particularly in the overweight and obese populations1, but in the face of persistent, severe, or recurrent symptoms, other diagnoses must be considered. These typically fall into two categories in children and adolescents: bony or structural causes2, or rheumatologic conditions3. Careful history and physical examination, along with use of imaging and laboratory studies, can often distinguish between the two4, 5. The following case describes an adolescent young man with severe ankle pain, as well as multiple other joint complaints, who was correctly diagnosed and treated for polyarticular juvenile idiopathic arthritis. While the majority of his joints improved, his ankle continued to be extremely tender and swollen. After two years of aggressive medical treatment, surgical procedures, and multiple imaging studies, it was careful probing into his history and classic physical examination findings that ultimately led to the additional diagnosis of gout.

Medical History

His past medical history was unremarkable. Family history was negative for autoimmune disease including JIA. His only medication was occasional ibuprofen, and his immunizations were up to date.

Examination and Laboratory Investigations

The patient weighed 142.8 kg and 173.6 cm tall, with a BMI of 47.4. His vital signs were normal and he was in no distress. Musculoskeletal exam revealed bilateral limited ankle dorsiflexion, worse on the right. He had tenderness to palpation over the medial aspect of his ankle just anterior to the medial malleolus. All other joints were normal. His initial work-up consisted of radiographs of his right ankle, showing evidence of a healing osteochondritis dissecans (OCD) lesion.

Radiographs showed the previously seen presumed OCD lesion, now with a sclerotic border. He was scheduled for an MRI of the ankle. Several months later, he began complaining of left shoulder pain and decreased range of motion of gradual onset. He was diagnosed with adhesive capsulitis. An MRI of the shoulder was performed given the unusual age of presentation for adhesive capsulitis, which revealed evidence of inflammation and synovitis consistent with juvenile idiopathic arthritis (JIA). The patient described daily pain and some morning stiffness for several weeks at a time, and pain and stiffness involved the right elbow, left knee, right wrist and several fingers in addition to the left shoulder and right ankle previously described .He was referred to the rheumatology service. Examination of RF + polyarticular JIA Subsequently, an anti-CCP antibody test was positive.

Management

Treatment was started with naproxen and methotrexate regimen. After treatment the patient presented for follow-up approximately 2.5 months. At that time, the pain in the majority of his joints had improved; however, the right ankle had become more tender and swollen. The pain was worse in the morning and he began using crutches. He was started on twice weekly etanercept injections, but when he experienced no relief, he switched to adalimumab and then to rituximab.

The lack of response of the patient’s ankle to this therapeutic regimen over the course of the next year, despite improvement in his other joints, arthroscopic exploration of the right ankle with synovectomy and potential OCD curettage was performed.

After recovery from surgery, the patient returned to the rheumatologist for further management of his JIA. He continued to have pain and stiffness of his right ankle and several other joints that was difficult to manage. He started on a low dose of prednisone. Ultimately the medication regimen of prednisone, etanercept, methotrexate, naproxen, and sulfasalazine had the greatest impact on his JIA symptoms, although his right ankle continued to be the most painful joint.

2.5 years after he first presented, the patient developed multiple non-tender scattered subcutaneous nodules over the extensor surface of his bilateral forearms, left elbow, and right knee. Four months later, the patient ankle pain seemed to worsen following the ingestion of red meat. With this new data, a uric acid level was elevated at 13.3 mg/dL. The patient was started on colchicine and then allopurinol and improved. He did begin to complain of pain in his big toe, a more classic presentation of gout. Uric acid levels however, remained high, running between 11.7 and 13.5 mg/dL over the following year. He continues to be treated for both JIA and gout.

Discussion

Joint pain is a common complaint in pediatrics and in the face of persistent, severe, or recurrent symptoms, the differential typically expands to include bony or structural causes versus rheumatologic conditions. In this case, however, diagnosis was complicated because the child had two distinct etiologies causing joint pain. Moreover, the second diagnosis was gout, a very uncommon condition in pediatrics, even in the setting of morbid obesity. Poly-articular JIA was considered as the unifying diagnosis when the patient presented with involvement of multiple joints. The typical presenting features of JIA are morning stiffness, pain and swelling of the joints, limited range of motion, and joint contractures6. The disease is thought to be idiopathic with its cause poorly understood, although there is mounting evidence that autoimmunity may be involved6. While the majority of the patient’s complaints did fit the diagnosis of JIA both in his clinical presentation and laboratory and imaging results, as well as his response to treatment, his right ankle continued to be refractory to treatment7. The acquisition of additional history led to the consideration of gout as a second diagnosis. Juvenile gout has begun to be reported, with many of the cases being due solely to known risk factors such as being overweight8, 9.

Gout can appear similar to other arthritides on MRI, with mild bone marrow edema, tenosynovitis, and bony erosions, making diagnosis difficult but important to consider, especially in overweight or obese patient10. Gout simulating JIA is a possibility; a patient with untreated gout can develop bony erosions and deformities, leading to the disappearance of the intercritical periods which are usually pathognomonic of gout. Typically, however, one would expect gout to present as an episodic arthritis. Even in untreated individuals, complete resolution of the earliest attacks nearly occurs within several weeks, which this patient never experienced. Moreover, the symmetric joint distribution with involvement of the PIPs along with a positive rheumatoid factor and CCP antibody point toward the concurrent JIA diagnosis in this case. Long term lifestyle consequences are being seen more frequently in the pediatric population, most notably type II diabetes but also musculoskeletal complaints and, as in this case, gout.

Learning

Gout was diagnosed in this teenage patient with longstanding JIA. The diagnosis of gout should therefore be an important element of the differential for a refractory painful joint in an overweight patient regardless of age, and regardless of pre-existing diagnoses. Failing to consider this diagnosis may result in delay of optimal treatment and cause long-term effects of bone erosion and joint destruction. Sending joint fluid for crystalline analysis, checking uric acid levels, and performing imaging studies, specifically non-invasive, cost effective modalities such as ultrasound, are all reasonable parts of a complete work-up in any child with arthritis.

References:

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  6. Gowdie PJ, Tse SM: Juvenile idiopathic arthritis. Pediatr Clin North Am 2012, 59(2):301–327.
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  9. Kedar E, Simkin PA: A perspective on diet and gout. Adv Chronic Kidnet Dis 2012, 19(6):392–397.
  10. Dalbeth N, Doyle AJ: Imaging of gout: an overview. Best Pract Res Clin Rheumatol 2012, 26(6):823–838
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